The present invention relates to apparatus for testing the pulmonary functions of a patient and more particularly to an interactive and fully automated-pulmonary function testing system.
The testing of pulmonary functions of a patient is, many times, beneficial toward providing an understanding of a possibly diseased condition or other physical defects affecting a particular patient. Typically, pulmonary function testing is divided into three main areas. The first type of pulmonary testing is generally referred to as spirometry which provides measurements in terms of volume and breathing rates of different patient inspiratory and expirarory efforts. In addition, various flow rates at various stages of a test are also the type of data generated from spirometry testing. A second area of pulmonary testing is a set of procedure designed to determine the uniformity of the distribution of inspired air throughout the lungs of a patient. By virtue of such tests, pulmonary insufficiency can be determined even though the alveolor ventilation of a patient is normal. A third type of pulmonary testing concerns the ability of the lungs to diffuse inspired air through alveolar membranes and such tests provide an indication of the ability of the lung to arterialize venous blood by exchanging oxyben for carbon dioxide.
Although the foregoing areas of pulmonary function testing are widely known and have been practiced for many years, nonetheless, such testing has not developed results which are entirely satisfactory. For example, spirometry testing has conventionally utilized a recording chart or strip device adapted to be driven by a spirometer in response to various breathing efforts by a patient under examination. However, the data obtained from such testing is generally read by an operator from the graph inscribed upon the recording strip by observing certain maximum and minimum values thereon. Thus, ample opportunity for error and disparate results are, and have been, a chronic problem of pulmonary function testing equipment as many times it is only the visual observation of an operator which is relied upon to develop necessary data. In addition, by requiring that data be read from a recording strip or the like, the observation and recordation of such data is relatively time-consuming and thus reduces the ability of such systems to rapidly and accurately test a number of patients in a given period of time. Furthermore, it has been found that operators must possess significant levels of skill in order to operate conventional pulmonary testing equipment and must be carefully trained to enable proper interpretation of data developed by such devices.
A further serious deficiency of prior art pulmonary function testing equipment has been the general lack of interaction between the operator, the patient, and the testing apparatus. For example, in certain pulmonary function testing such as dynamic compliance tests, which will be described in greater detail hereafter, it is highly important in order to obtain valid data that the patient breathe at a constant rate of, for example, 30, 60 or 90 breaths per minute. Previously, the breathing rate of a patient was either monitored visually by an operator or assisted by means of a metronome or like device although neither technique effectively assured such constant breathing rates. Accordingly, an interactive testing system wherein such breathing rates are continually monitored during the acquisition of pressure and volume data necessary for such dynamic compliance tests such that necessary instructions for maintaining or altering a breathing rate may be displayed to a patient, is clearly a feature to be desired on pulmonary function testing equipment and which is a feature which has been lacking in prior art systems.